A meta-analysis on endurance athletes’ training found that while high-intensity interval training (HIIT) above the maximal metabolic steady state (MMSS) significantly improved oxygen uptake (V̇O2peak), there was no detectable difference in time-trial (TT) performance. This suggests that although increased V̇O2peak is achievable through HIIT, translating it into enhanced TT performance may require a different approach or potentially longer timeframes. The findings may inform athletes on balancing low/intermediate intensity and HIIT sessions.